1. Field of the Invention
This invention relates generally to the air conditioning of an emergency vehicle or the like and more particularly to the cooling or heating of the rear area of the vehicle, occupied by an injured person and emergency personnel.
2. Description of the Prior Art
A study of the prior art reveals that various methods and arrangements have been developed to air condition emergency vehicles or the like. There are two principal refrigeration type air conditioning systems currently employed in such vehicles, with the first of these being an air-conditioning system in which the Freon compressor is driven by the vehicle""s engine. The second is a separate system which is operable when the vehicle may be parked and employing a motor-driven compressor, powered by an outside ac line voltage source or the equivalent.
If there is no alternating current line voltage available when the vehicle is parked, the vehicle engine can be started and idled so that the rear area can be air conditioned. As an alternative to this, a small separate generator powered by gasoline or Diesel engine can be utilized.
As one example of prior art devices, the Dawkins Patent No. 3,984,224 entitled xe2x80x9cAir Conditioning System for a Motor Home Vehicle or the Like,xe2x80x9d is concerned;with cooling both the front passenger area as well as the rear living area. This patentee describes that he uses over-sized condensers mounted on the roof of his vehicle so that both the front and rear areas of the vehicle can be cooled without necessitating the use of separate air conditioning systems. Although Dawkins describes that he may use either a compressor driven by the vehicle""s engine or an ac line voltage source driving a 110 volt electric motor driven compressor, this patentee shows no recognition of the fact that his evaporators can be disposed in a compact arrangement. Also, his roof-mounted condensers are a considerable disadvantage when the vehicle is brought near a low overhang or low roof.
The prior art also teaches the use of certain combinational schemes for the providing of cooled or heated air to a vehicle. Although not designed for use with an emergency vehicle, the Pannell U.S. Pat. No. 5,307,645 nevertheless teaches a dual stage system utilizing interleaved evaporator coils. This patentee describes that Compressor Q1 is a first stage compressor whose suction port is connected to the evaporator coil 52, with the suction port of the Compressor Q2, the second stage compressor, being connected to the evaporator coil 54. Pannell utilizes a single evaporator fan 49 which induces the return air R to flow through the evaporator unit 30 depicted in Pannell""s FIG. 4, in which unit, both evaporator coils are disposed. However, this patentee exhibits no-recognition of the use of an evaporator unit in which the separate evaporator coils (tubing arrays) of two different, separately operable air conditioning systems are placed in a contiguous arrangement such as to make possible the use of a single blower.
The Loup U.S. Pat. No. 5,884,696 teaches a triple heat exchanger occupying less space than the combination of two separate heat exchangers. Three fluids are dealt with, involving air for delivery into the cabin of a vehicle; a refrigerant fluid such as to pass from the liquid to the gaseous state in the heat exchanger by absorption of heat; and a hot fluid which yields heat to the other two fluids. However, this patentee exhibits no recognition of an arrangement in which a single, compact evaporator unit could be advantageously employed with two alternatively operable air conditioning units.
A combinational air conditioning arrangement for an emergency vehicle or the like in accordance with this invention is designed to be used with a compressor driven by the vehicle""s engine or, alternatively, by a compressor driven from a suitable 110 volt source. My novel system comprises an evaporator supporting means, and a novel air conditioner evaporator unit mounted upon the supporting means. This novel evaporator unit involves closely spaced first and second tubing arrays or cores, with each array being operably associated with a respective refrigerant compressor. The tubing of each array is formed into coils involving a number of essentially parallel tubing runs connected by curved end members. A third tubing array is operatively positioned alongside the evaporator involving the first and second tubing arrays, with this third tubing array being adapted to carry a heated liquid on selected occasions.
Advantageously the first and second tubing arrays are interconnected by a multiplicity of fin members of thin, thermally conductive material, and in many instances, the fins are constructed so as to include the third tubing array as well.
As will be understood by those skilled in the art, the first and second tubing arrays operate independently and alternatively, with refrigerant actively flowing through one or the other of the tubing arrays at a given time.
It is most important to note that I utilize blower means common to all three tubing arrays, with this blower means operative on low voltage, typically 12 volts dc. This is to say, even though the vehicle is parked, and the Freon compressor powered by 110 volts ac is in operation, the functioning of the low voltage blower means remains unaffected.
It is a primary object of my invention to provide a compact evaporator unit primarily constructed for use in a space-saving manner in an emergency vehicle, with this evaporator unit featuring closely spaced first and second tubing arrays or cores, each operably associated with a respective compressor, with a third tubing array operatively positioned alongside the first and second tubing arrays and adapted to carry a heated liquid on selected occasions.
It is another object of my invention to provide a system wherein the several fans relating to the air conditioning system, as well as the air circulating blower are, quite advantageously, each driven by a 12 volt dc system.
It is yet another object of my invention to provide a single thermostat for the operation of two independent heating and cooling systems, thus eliminating unnecessary wiring and minimizing space requirements in the rear, patient carrying compartment of the vehicle.
These and other objects, features and advantages will become more apparent as the description proceeds.